About a third of the way. That’s when Dan Gargaro realized he was on the path to victory at the 2019 Long Island Marathon.

“Somewhere between mile eight and mile nine, one of the bikers (bicycle riding escorts) said, ‘I can’t see second place,’” said Gargaro, a Sayville Running Company member and weekend employee at the Main Street sneaker and running apparel shop. “I had a two-and-a-half-minute lead halfway through the race, and at mile 21, I didn’t see anybody behind me.”

By the time Gargaro, 29, of West Islip crossed the finish line in Eisenhower Park — 26.2 miles from the starting line — his lead had ballooned to nearly seven minutes.

The former West Islip High School cross country and track star finished the rainy May 5 race in 2:30:15.

Amazingly, it was Gargaro’s second marathon win in three tries.

“It’s a pretty good winning percentage. I definitely won’t keep that over a lifetime,” said Gargaro, who won the Central Park Marathon in 2016. He also finished the Boston Marathon in 2017.

Dan Gargaro, 29, finished the 2019 Long Island Marathon in 2:30:15.

With the finish line in sight at the Long Island Marathon, Gargaro said he felt “over the moon” as his wife Michelle and parents, Laurie and Salvatore, cheered him on.

“A marathon is one of those things where so many things have to go right in order to run the perfect race,” said Gargaro, who works full time for the New York State Insurance Fund.

Gargaro said he was motivated by what he labeled a poor performance two years ago in the Boston Marathon. He needed three hours and 17 minutes to finish those 26.2 miles — good enough for 4,035th place.

“It was a very hot day and I went out a little too fast,” he said. “The temperature spiked at mile six, and by mile 20, I was walking. When I crossed the finish line, I needed a wheelchair and had an IV stuck in me.”

He said the humbling experience in Massachusetts taught him a lot about marathon running.

“I learned a lot from that one. I learned how take water better, and that sunblock helps keep you hydrated,” said Gargaro, who aims to exercise his Boston Marathon demons by returning for another crack at the classic race.

For the time being though, he’s content to bask in the glow of his Long Island win — and an exceedingly high .667 winning percentage.